Desalination is a process of removing dissolved salts and other minerals from seawater or brackish using certain technological procedures, in order to get clean drinking water, irrigate agricultural areas and for other purposes. The process of desalination can be divided into two basic groups: thermal processes and membrane processes. Reverse osmosis membrane processes are most commonly used globally while thermal processes are used in countries with available energy resources such as Middle East countries. Although the desalination processes are expensive because of energy costs by investing in technology development we try to achieve greater efficiency with lower costs. Environmental impact of desalination is best reflected in the large amount of concentrate discharges to the marine environment which have a negative effect on the ecosystem, as well as in the green house gas emissions produced by burning fossil fuels. This is why it is important to take care of disposal and management of the concentrate prior to its discharge into the environment.